JPH0669625B2 - Automatic welding method for square members - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic welding method for a square member such as a joint core used at a joint between a column and a beam.

[Prior Art] A joint core in a steel structure is used at a joint between a steel column and a steel beam such as H-section steel as shown in Figs. 9 and 10. In the above, 30 is a connection core, 34 is a steel column, and 36 is a steel beam.

Such a joint core 30 generally has a rectangular rectangular column 31.
And a diaphragm 32 welded to the upper and lower ends of the column 31 for transmitting the stress from the beam 36. The joint between the column 31 and the diaphragm 32 is usually a butt joint, and the shape of the groove 33 thereof is generally a L-shape as shown in FIG. The joint core 30 is manufactured by performing the multi-pass welding on the groove 33. In addition, in FIG. 11, 38 is a backing.

Then, the end face of the column 34 is welded to the surface of the diaphragm 32 of the joint core 30, while the end face of the beam 36 is welded to the side of the diaphragm 32 and the face of the column 31, thereby constructing a steel structure. .

Although the joint core 30 has a relatively simple shape, the welding line between the rectangular column 31 and the diaphragm 32 is a combination of a straight line portion corresponding to the side of the column 31 and an arc portion corresponding to the corner portion. Therefore, since it is particularly difficult to weld at the corner portion, conventionally, the straight portion and the corner portion are separately welded by semi-automatic welding. However, if the straight part and the corner part are welded separately, inefficiency is increased and the seam of the weld bead increases, which may cause welding defects or lead to defective bead shape. There was a problem. Therefore, automation of welding is required. For this reason, it is possible to use welding robots. However, even in the case of such automatic welding, not only it is necessary to change the welding conditions (welding speed, current, etc.) at the straight line portion and the corner portion, but also in general for multi-layer welding. Since welding is used, there is a problem that it takes a lot of time and effort to create a welding program. Furthermore, the column 31 is not always good in terms of accuracy, which makes the automation of welding even more difficult.

[Problems to be Solved by the Invention] It is clear that the most problematic problem in automatic welding of the joint core 30 is welding at the corner portion of the column 31. One of them is the optimization of the welding speed at the corners and the smoothing of the bead shape. That is, when a welding line including a straight line portion and a circular arc portion is placed in the vertical plane, if the welding speed at the corner portion is inappropriate, not only the same bead height as the straight line portion cannot be obtained, but also the speed is temporarily reduced. Even if it is proper, if the turning timing of the joint core is at the same time when the arc point enters on the arc part of the corner, the center of gravity of the molten pool is located behind the arc point. As a result of the upward welding, the cross-sectional shape of the bead is likely to be convex, and the bead height is not uniform and is distorted, which impairs the smoothness of the bead shape. Therefore, as a measure against this, make the molten pool as small as possible,
In other words, it is necessary to reduce the center of gravity of the molten pool so that it approaches the arc point, and it is necessary to consider the timing of switching to the welding speed at the corner, that is, the timing of rotation of the joint core.

Therefore, an object of the present invention is to provide an automatic welding method in which the welding speed is optimized and the bead shape is smoothed, particularly in the automatic welding of a square member such as a joint core.

[Means for Solving the Problems] In order to achieve the above object, an automatic welding method for a rectangular member according to the present invention is a rectangular member in which a welding line is placed in a vertical plane and includes a straight portion and an arc portion. In the automatic welding of, the welding groove is welded using a welding robot and a positioner including means for attaching a square member and rotating it by a predetermined angle. In this case, when the welding current value is a straight line portion in the arc portion. If the welding speed is made lower and the welding speeds in the straight line portion and the arc portion are respectively set to v _s and v _c, and the feeding speeds of the electrode wires are set to v _fs and v _fc , respectively, the welding speed v _c in the arc portion is The square member is rotated in synchronism with the operation of the welding robot so as to satisfy the following formula, and the rotation timing is set when the arc point during welding enters from the straight line portion to the arc portion by a distance of l. Is. Here, 1 is the distance from the arc point to the center of gravity of the molten pool.

Here, h is the height of the weld bead, and r _i is the inner circumference radius of the weld bead of the i-th layer of the arc portion.

[Operation] The groove is welded to the square member attached to the positioner by the welding robot. In this case, the weld line lies in the vertical plane and includes straight and circular sections. Then, with respect to the straight line portion, the welding current value _Is , the wire feeding speed _vfs
And welded at a welding speed v _s, decreased welding current values for the I _s lower welding current value I _c, likewise the v slower than _fs wire feed rate v _fc and the v _s with respect to the circular arc portion especially involving wire feed rate welding speed v _c for the variation was expected in _correction, specifically welded at welding speed v _c that satisfies equation (1). That is, if the welding current value at the arc portion is made lower than that at the straight portion, the molten pool becomes smaller and the position of the center of gravity approaches the arc point, so that the state of upward welding can be almost eliminated. However, if the welding current value is lowered, the wire feeding speed is naturally slower in the arc portion. Therefore, in order to make the bead height the same, it is necessary to correct the welding speed in consideration of the change in the wire feeding speed. . As a result, the bead height does not change even in the arc portion, and the smoothness of the bead shape can be maintained.

Further, during welding of the arc portion, the positioner operates in synchronization with the welding robot. Therefore, when the welding torch enters a distance of 1 from the straight line portion beyond the starting point of the circular arc portion, the square member is rotated by a predetermined angle by the positioner. Then, since the tangent line at the center of gravity of the molten pool is always horizontal, the state of the upward welding can be completely eliminated in combination with the reduction of the molten pool due to the above action. As a result,
The bead shape at the arc is surely smooth. The above l is the distance from the arc point to the position of the center of gravity of the molten pool, and is mainly related to the welding current value. Therefore, in determining l, it is necessary to obtain it by trial welding.

Then, an arc point reaches the end of its arc portion, to increase at the same time welding current values, and the welding speed from the v _c v
_s and weld the next straight part at this speed v _s .
The rotation of the rectangular member ends when the arc point enters the straight line portion by the distance l from the end point of the arc portion. After that, by repeating the same operation, the square member can be automatically welded continuously around the entire circumference.

Embodiment An embodiment of the present invention will be described below with reference to the drawings. 1 (a) to 1 (c) are explanatory views of the operation in the case where the welding line of the joint core is continuously welded all around continuously, and FIG. 2 shows the rotation timing of the joint core at one corner thereof. FIG. 7 is a detailed operation explanatory diagram. In this case, the weld line 10 is placed in the vertical plane,
It includes straight portions 11a, 11b, 11c, 11d and corner portions 12a, 12b, 12c, 12d. The welding torch 1 is perpendicular to the welding line 10 and inclined rearward or forward (front and back direction of the paper) at a constant angle, and at the corner portion, its axis is directed toward the center of curvature of the corner portion. Attitude is controlled. The groove cross-sectional shape is uniform over the entire circumference.

In FIG. 1, the contour shape of the cross section of the joint core 30 is shown by a broken line, and the joint core 30 is attached to a positioner as described later and is controlled so as to operate in synchronization with the welding robot.

The welding operation will be described with reference to FIGS. 1 and 2. First,
The welding start point A is set at an appropriate position on the horizontal straight line portion 11a (see FIG. 1 (a)). The starting point A and the positions of the connecting points B, C, D, ..., I between the respective straight lines and corners are stored in a controller (not shown) by the size of the joint core 30 or the teaching by the welding robot. It is stored in the department. Further, the distance of l is also stored in the storage unit in the same manner. Further, the welding current value is changed and set corresponding to the straight line portion and the corner portion. That is, less than _{I s} When the straight portion at the corner portion value _{I c} (usually 10-30%
Reduced). Further, the feeding speed of the electrode wire 2 is also changed from v _{fs in the} straight portion to v _fc in the corner portion, and the wire feeding speed becomes slower as the welding current value decreases. v _c above
According to the equation (1), it is controlled so as to compensate for the change in the wire feeding speed. Therefore, from the welding start point A to the starting point B of the first corner portion 12a is welded at a pre-set welding speed v _s. The welding current value at this time is I
_s and the wire feed rate is v _fs . Then the first
To welding speed v _s is the point B of the corner portion 12a, the
(1) Change in welding speed v _c satisfying the formula, and starts rotating the Joint core when the arc point to a position B ₁ that entered the first corner portion 12a of the point B by l reaches, first Corner 12
Welding is carried out so that the 90 ° rotation of the finish core is completed when entering the next straight portion 11b from the end point C of a by 1. The welding current value I _{c at} this time is lower than the welding current value I _s of the straight line portion, and accordingly, the wire feeding speed v _fc is also slower than the wire feeding speed v _{fs of the} straight line portion. Therefore, in order to obtain the same bead height at the corner portion as at the straight portion, the welding speed v _c
It is necessary to make a correction in consideration of the change in wire feeding speed. In addition, in the case of corner welding,
As will be described later, welding is performed while simultaneously rotating the joint core 30 by 90 °.

Next, description will be given with reference to FIG. 3 in obtaining the welding speed v _c of the above corner portion. First, it is assumed that the groove has a uniform cross-sectional shape in both the straight portion and the corner portion.

A welding amount W _s when a corner portion having an inner surface radius of curvature r _i is moved at a welding speed v _s to obtain a bead height h in a straight line portion,
The ratio with the welding amount W _c when the corner portion having the curvature radius r _i is moved at the welding speed v _c for obtaining the same bead height h at the corner portion is expressed as follows.

Further, the welding amount W when moving the corner portion of the radius of curvature r _i at the speed v and the wire feeding speed v _f is Therefore, Therefore, Thus, the above equation (1) is obtained.

Now, if the wire feeding speed is the same for both the straight and corner portions and only the welding speed is changed, v _fc /
Since _vfs = 1, the welding speed _{vco at} the corner at this time is Becomes Therefore, if the wire feed rate is constant,
If the welding speed of the corner portion is controlled according to the equation (2), the bead height h of the corner portion can be made equal to that of the straight portion. However, the corner welding is generally in the state of upward welding. This will be described with reference to FIGS. 4 and 5.

In arc welding, the arc point 3 and the center of gravity G of the molten pool 4 do not match as shown in FIG. This distance 1 is mainly related to the welding current value, and the welding current value I = 250 A and 1 = 5 to 6 mm. Therefore, assuming that the joint core 30 starts to rotate when the arc point 3 reaches the R stop at a certain corner portion (the connection point between the straight portion and the corner portion), as shown in FIG. The tangent line 5 at the center of gravity position G of the molten pool 4 is not horizontal, and has an inclination angle α (≈l / r _i ) with the horizontal line 6.

The inclination angle α at the corner is shown in FIG. 5 (b). In the figure, v _s is the welding speed of the adjacent straight line portion.

In this way, the center of gravity of the molten pool 4 is always exposed to the upward gradient at the corners, and thus the state of upward welding is produced, and the cross-sectional shape of the bead 7 becomes convex as shown in FIG. 6 (a). In addition, the bead height h is not the same as that of the straight line portion and is distorted as shown in FIG.

Therefore, by lowering the welding current value at the corner portion, the molten pool 4 is made as small as possible, thereby bringing the center of gravity position G of the molten pool 4 close to the arc point 3. Further, by setting the rotation timing of the finish core 30 to be the time when the arc point 3 reaches the point B ₁ where the arc portion 3 enters the corner portion 12a from the straight portion 11a, the center of gravity position G of the molten pool 4 is determined.
The tangent line 5 at is always horizontal, and the state of upward welding can be completely eliminated. As a result, the bead shape becomes smooth without causing the above-mentioned problem of the bead shape. Of course, the bead height does not change.

Therefore, in the present invention, the welding current value is lowered at the corner portion, and the change in the wire feeding speed due to it is taken into consideration. It is obtained by the time that the welding speed v _c according to the above (1), and containing a predetermined distance l to the corner portion on the rotation period of the Joint core 30.

Returning to FIG. 1 again, the rotation of the joint core 30 will be described. When the welding torch 1 reaches the point B ₁ , the position is rotated by 90 ° about the point O by the positioner. At the same time, the welding torch 1 is moved in synchronization with this rotating operation (see FIG. 1 (b) and FIG. 2). Needless to say, the welding current value and the wire feeding speed are also switched to the values I _c and v _fc that are smaller than those in the case of the straight portion as described above. Further, welding speed v _c of the first corner portion 12a during the rotation of the Joint core 30 is controlled so as to satisfy the above equation (1). By the way, the locus of motion B ₀ −B−B ₂ (1
Since 5) is known, the trajectory of the torch 1 can be easily obtained from the trajectory 15 of this point B, and
The welding speed v _c during the rotation of 30 is the above relative to the moving speed of the point B, that is, the rotational speed (known) of the positioner.
It can be controlled so as to satisfy the equation (1).

Explaining the means for realizing the welding speed v _c in the arc portion of any one corner, in FIG. 7, L ₁ : the length of the vertical side of the welding line L ₂ : the length of the horizontal side of the welding line R: arc Radius of curvature of the center of curvature of the part r: radius of arc part, length of arc part at one corner = πr / 2 Robot movement distance when welding the arc part = πR
/ 2 where When L ₁ = L ₂ Therefore, the robot moving speed v _{c (Rob)} for realizing the welding speed v _c is Becomes Therefore, begin to rotate the positioner when the torch in the corner portion inlet has reached, the robot may be moved on the arc of a radius R at a rate R / r × v _c.

It should be noted that the rotation speed of the positioner may be 90 ° while the torch moves on the arc of one corner (t), The rotational angular velocity of the positioner is Becomes

When the welding torch 1 reaches the end point C of the first corner portion 12a, the welding speed is switched from v _c to v _s , and the welding current value and the wire feeding speed are also changed from I _c to a higher I _s . , _Switch from v _fc to faster v _fs ,
The next second straight portion 11b is welded at this welding speed v _s (see FIG. 1 (c)). After that, as in the above, the second corner
12b, third straight portion 11c, third corner portion 12c, fourth straight portion 11d,
Then, the welding is performed in the order of the fourth corner portion 12d, and returns to the welding start point A of the first straight portion 11a to make one round. The above operation is repeated for the second and subsequent layers. In this way, the joint core 30 can be automatically welded over the entire circumference.

Next, FIG. 8 is a perspective view of a welding apparatus for performing the above-described automatic welding. This apparatus is a positioner for performing a synchronous operation with the multi-joint welding robot 20 and the joint core 30 attached.
It consists of 24 and.

The positioner 24 has a rotary table 25 on which the joint core 30 is horizontally mounted in a cantilever manner. The rotary table 25 rotates the joint core 30 by a predetermined angle. The operation is performed in synchronization with the operation of the welding robot 20 as described above.

As is clear from the above description, the welding line 10 is not limited to a quadrangular shape, but can be similarly applied to a polygonal shape, that is, a triangular shape, a pentagonal shape, a hexagonal shape, or the like.

[Effects of the Invention] As described above, according to the present invention, a welding robot and a positioner are used to continuously and automatically perform welding on a square member whose welding line is placed in a vertical plane and which includes a straight line portion and a circular arc portion. Welding is possible, the welding current value in the arc portion is lower than that in the straight portion, and the welding speed v _c is the welding speed v in the straight portion.
_{Since s} is switched so as to satisfy the above formula (1) and the rotation time of the rectangular member enters the arc portion by a predetermined distance l, the arc portion is welded. The molten pool in becomes smaller, its center of gravity approaches the arc point, and the tangent at that center of gravity is always horizontal, so the state of upward welding can be completely eliminated,
As a result, there is an effect that the bead height can be made smooth with the same bead height as the straight line portion.

[Brief description of drawings]

1 (a) to 1 (c) are explanatory views of the operation of the method for automatically welding a square member according to the present invention, and FIG. 2 is an explanatory view showing the rotation timing of the square member at a corner portion (arc portion), FIG. 3 is an explanatory diagram for obtaining the welding speed at the corner portion, and FIG. 4 is a relational diagram of the distance l between the arc point and the center of gravity of the molten pool,
FIGS. 5 (a) and 5 (b) are views showing a state in which the tangent line at the center of gravity of the molten pool at the time of rotation of the square member indicates an inclination angle and a state in which the inclination angle changes, and FIGS. b) is a diagram showing the bead shape of the corner portion when a large melt pool, Fig. 7 is a diagram used means for implementing the welding speed v _c in the circular arc portion, FIG. 8 is used in an automatic welding process of the present invention 9 is a perspective view of the joint core, FIG. 10 is a perspective view of the joint core, and FIG. 11 is a sectional view of the groove in the joint core. 1 ... Welding torch 2 ... Electrode wire 3 ... Arc point 4 ... Molten pool 10 ... Welding line 11a-11d ... Straight line part 12a-12d ... Corner part (arc part) 20 ... Welding robot 21 ... Arm 24 ... Positioner 25 ... Rotary table 30 ... Connection core 33 ... Groove

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenichiro Yamashita, 20 Ishigane Co., Ltd., Toyama City, Toyama Prefecture (72) Hideaki Kanayama 20, 20 Ishigane, Toyama City, Toyama Prefecture

Claims (1)

[Claims] 1. In automatic welding of a square member having a welding line in a vertical plane and including a straight line portion and a circular arc portion, a welding robot and a positioner including a means for mounting the square member and rotating the square member by a predetermined angle. Are used to weld the groove, and in this case, in the arc portion of the welding line, the welding current value is made lower than that in the straight portion, and the welding speed in the straight portion and the arc portion are respectively set to v _s , v _c and the feeding speeds of the electrode wires are v _fs and v _fc , respectively,
Welding speed v _c in the arcuate portion is rotated the angle-shaped member is synchronized with the operation of the welding robot so as to satisfy the following equation, further the rotation timing arc point during welding of the molten pool from the arc point An automatic welding method for a rectangular member, characterized in that the arc portion is welded when the arc portion is entered from the straight portion by a distance 1 to the position of the center of gravity. Here, h: height of weld bead r _i : inner radius of weld bead of i-th layer of arc portion